def main():
    n = input("Input a number: ")
    print("Fibonacci number of {0} is {1}".format(n, fibonacci(int(n))))

def fibonacci(n: int):
    a, b, count = 0, 1, 1
    while count < n:
        count += 1
        a, b = b, a+b
    return b

if __name__ == "__main__":
    main()